diff --git a/.travis.yml b/.travis.yml
index 6f6be0f1..09ef5985 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -16,6 +16,7 @@ cache:
 env:
   - USE_OPTIONAL=true
   - USE_OPTIONAL=false
+  - SIX_VERSION=1.9 USE_OPTIONAL=true
 
 install:
   - bash requirements-install.sh
diff --git a/requirements-install.sh b/requirements-install.sh
index cd693444..0be226a6 100755
--- a/requirements-install.sh
+++ b/requirements-install.sh
@@ -11,6 +11,10 @@ if [[ $USE_OPTIONAL == "true" ]]; then
   pip install -U -r requirements-optional.txt
 fi
 
+if [[ $SIX_VERSION != "false" ]]; then
+  pip install six==$SIX_VERSION
+fi
+
 if [[ $CI == "true" ]]; then
   pip install -U codecov
 fi
diff --git a/requirements.txt b/requirements.txt
index 745993b9..3884556f 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,3 +1,3 @@
-six
+six>=1.9
 webencodings
 ordereddict ; python_version < '2.7'
diff --git a/setup.py b/setup.py
index 00fee241..6f0fc17e 100644
--- a/setup.py
+++ b/setup.py
@@ -102,7 +102,7 @@ def default_environment():
       maintainer_email='james@hoppipolla.co.uk',
       packages=find_packages(exclude=["*.tests", "*.tests.*", "tests.*", "tests"]),
       install_requires=[
-          'six',
+          'six>=1.9',
           'webencodings',
       ],
       extras_require={